1. Field of the Invention
The present invention relates to an apparatus for the detection of magnetically conductive metals in a moving flow of material, and of the type comprising a metal casing which is open at its ends and has a substantially square cross section, the material flow passing through said casing.
2. Description of the Prior Art
In metal smelting plants in which the raw material used is nonmagnetic scrap metal, it is often necessary to know whether there are magnetizable metals, such as iron, among the scraps. Iron is often present in a coppered form, and the copper may be diffused into broken and cut surfaces, in which case visual detection is impossible. Finding magnetically conductive metals in a pile of non-magnetic scrap or in a non-magnetic scrap bale with the aid of permanent magnets is a known method, but it is inconvenient, time-consuming, and sometimes even impossible, since permanent magnets must have mechanical contact with the metal pieces to be inspected in order to detect magnetism.
It is also a known method to measure the material to be inspected in a static magnetic field and to use detectors to observe the effect of the pieces present in the material on the magnetic field, i.e., their magnetism.